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Mem. Inst. Oswaldo Cruz ; 116: e200571, 2021. tab, graf
Article in English | LILACS | ID: biblio-1154878


Leishmania infantum chagasi is the causative agent and Lutzomyia longipalpis is the main vector of visceral leishmaniasis in the Americas. We investigated the expression of Leishmania genes within L. longipalpis after artificial infection. mRNAs from genes involved in sugar and amino acid metabolism were upregulated at times of high parasite proliferation inside the insect. mRNAs from genes involved in metacyclogenesis had higher expression in late stages of infection. Other modulated genes of interest were involved in immunomodulation, purine salvage pathway and protein recycling. These data reveal aspects of the adaptation of the parasite to the microenvironment of the vector gut and reflect the preparation for infection in the vertebrate.

Animals , Psychodidae/parasitology , Leishmania infantum/genetics , Insect Vectors/parasitology , Leishmania/isolation & purification , Leishmaniasis, Visceral/transmission , Psychodidae/genetics , Brazil , Gene Expression , Reverse Transcriptase Polymerase Chain Reaction/methods , Leishmaniasis, Visceral/parasitology , Leishmaniasis, Visceral/epidemiology , Life Cycle Stages
Medicina (B.Aires) ; 80(2): 103-110, abr. 2020. tab
Article in English | LILACS | ID: biblio-1125049


To diagnose dogs infected by Leishmania infantum rK39 rapid diagnosis test is widely used in the Americas, while dual path platform (DPP) was recently adopted by Brazil. In this study we assessed the performance of rK39-RDT and DPP tests in recent urban transmission scenarios of Argentina. The sensitivity and specificity were evaluated with a sera panel and field samples, taken as true infected those from parasitological and/or PCR positive tests. Since none of these tests can be taken as a gold standard, the performance was also evaluated using Latent Class Analysis, a statistical modeling technique which allows to estimating sensitivity and specificity defining a latent class variable as the reference standard. The sensitivity of both tests in the panel was around 92% (symptomatic dogs 96%, asymptomatic 83%), while the sensitivity in field samples of rK39-RDT was 77%, and DPP 98% (mean in symptomatic dogs 89%, asymptomatic 82%). The specificity was similar for both tests and samples, around 98%. Therefore, these tests are acceptable for program dog population-based studies, as spatial stratification, focus intervention and follow up, and they could be used for individual screening and confirmation of clinical presumptive diagnosis in polysymptomatic dogs. The inability to discriminate between immunity and actual infectiousness suggest that a combination with other non-immunological based tests will be required for highly sensitive/specific diagnosis in order to targeting control measures in individual reservoirs from public health perspective, as for individual management from animal health perspective.

Para diagnosticar perros infectados por Leishmania infantum, en las Américas se utiliza ampliamente la prueba rápida rK39, mientras que DPP fue adoptado recientemente por Brasil. En este estudio se evaluó el desempeño de las pruebas rK39-RDT y DPP en escenarios de transmisión urbana reciente en Argentina. La sensibilidad y especificidad se evaluaron con un panel de sueros y muestras de campo, considerando muestras infectadas verdaderas aquellas con pruebas parasitológicas y/o de PCR positivas. Como ninguna de estas pruebas puede considerarse estándar de oro, el desempeño también se evaluó mediante análisis de clases latentes, una técnica de modelado estadístico que permite estimar sensibilidad y especificidad definiendo una variable de clase latente como estándar. La sensibilidad de ambas pruebas en el panel fue de alrededor del 92% (perros sintomáticos 96%, asintomáticos 83%), mientras que la sensibilidad en muestras de campo fue rK39-RDT: 77%, y DPP 98% (media en perros sintomáticos 89%, asintomáticos 82%). La especificidad fue similar para ambas pruebas y muestras, cerca de 98%. Por lo tanto, estas pruebas son aceptables para estudios programáticos caninos de base-poblacional, como estratificación espacial, intervención de foco y seguimiento, y podrían utilizarse para el tamizaje individual y la confirmación del diagnóstico clínico presuntivo en perros poli-sintomáticos. La incapacidad de discriminar entre inmunidad e infectividad real sugiere que se requerirá una combinación con otras pruebas, de base no inmunológica, para un diagnóstico suficientemente sensible/específico que permita definir las medidas de control en reservorios individuales, tanto para salud pública, como para la gestión individual en salud animal.

Animals , Dogs , Dog Diseases/diagnosis , Leishmaniasis, Visceral/veterinary , Argentina , Brazil , Enzyme-Linked Immunosorbent Assay/veterinary , Polymerase Chain Reaction/veterinary , Sensitivity and Specificity , Dog Diseases/transmission , Leishmaniasis, Visceral/diagnosis , Leishmaniasis, Visceral/transmission
Rev. bras. parasitol. vet ; 29(4): e017820, 2020. graf
Article in English | LILACS | ID: biblio-1144228


Abstract Leishmania infantum infection in cats has been reported in several countries, including Brazil. However, the transmission of visceral leishmaniasis (VL) from cats to another host has not been proven yet. Therefore, the aim of this study was to verify the possibility of L. infantum transmission from cats to dogs. In order to verify the possibility of VL transmission from the cat to the dog, xenodiagnosis was carried out in a VL-positive cat, using 55 female Lutzomyia longipalpis. Five days later, 40 insects were dissected to verify Leishmania infection. The remaining 15 females were fed in a healthy dog. The potential infection of the dog was verified through clinical, serological, parasitological examinations, and PCR, at three, six, and twelve months post-infection. All 55 L. longipalpis females became visibly engorged. Leishmania promastigotes were detected in 27.5% of the dissected insects. Leishmania infection in the dog was confirmed upon first evaluation. DNA sequencing of the parasite isolated from the cat confirmed L. infantum infection and showed 99% similarity with the L. infantum DNA sequences from the dogs. Through this study, it was possible to confirm the L. infantum experimental transmission from a domestic cat to a domestic dog through its biological vector L. longipalpis.

Resumo A infecção por Leishmania infantum em gatos tem sido relatada em vários países, incluindo o Brasil. No entanto, a transmissão da leishmaniose visceral (LV) de gatos para outro hospedeiro ainda não foi comprovada. Portanto, o objetivo deste estudo foi verificar a possibilidade de transmissão de L. infantum de gatos para cães. Para verificar a possibilidade de transmissão da LV do gato para o cão, foi realizado xenodiagnóstico em um gato com LV, utilizando-se 55 fêmeas de Lutzomyia longipalpis. Cinco dias depois, 40 insetos foram dissecados para verificar a infecção por Leishmania. As 15 fêmeas restantes foram alimentadas em um cão saudável. A possível infecção no cão foi verificada por meio de exames clínicos, sorológicos, parasitológicos e PCR, três, seis e doze meses após a infecção. Todas as 55 fêmeas de L. longipalpis ficaram visivelmente ingurgitadas. Promastigotas de Leishmania foram detectadas em 27,5% dos insetos dissecados. A infecção por Leishmania no cão foi confirmada na primeira avaliação. O sequenciamento do DNA do parasito isolado do gato confirmou a infecção por L. infantum e apresentou 99% de similaridade com sequências de DNA de L. infantum de cães. Através deste estudo, foi possível confirmar a transmissão experimental de L. infantum de um gato doméstico para um cão doméstico através do seu vetor biológico L. longipalpis.

Animals , Female , Cats , Dogs , Cat Diseases/parasitology , Cat Diseases/transmission , Leishmania infantum/genetics , Dog Diseases/parasitology , Dog Diseases/transmission , Leishmaniasis, Visceral/transmission , Psychodidae/parasitology , Brazil , DNA, Protozoan/chemistry , Insect Vectors/parasitology , Leishmaniasis, Visceral/veterinary
Rev. bras. parasitol. vet ; 29(4): e016620, 2020. graf
Article in English | LILACS | ID: biblio-1144227


Abstract The main clinical, anatomopathological, and molecular aspects of the infection by Leishmania infantum are described in two cats with multicentric cutaneous, nodular, and ulcerated lesions. The animals were submitted to a clinical examination, followed by serological, molecular and parasitological exams, with culture and isolation of the parasite, and subsequent isoenzymatic characterization. The animals were euthanized and necropsied. Case 1 was an adult, female, mixed-bred stray cat. Case 2 was an adult, male, mixed-bred and domiciled cat. Both were positive for the presence of anti-L. infantum antibodies. In the cytology of the cutaneous nodules and lymph nodes, amastigote forms of Leishmania spp. could be visualized, free and in the interior of the macrophages. In the histopathology, the lesions were characterized by nodular granulomatous and/or ulcerative dermatitis, associated to amastigote forms of Leishmania spp. By means of the polymerase chain reaction, the sequence of the L. infantum kDNA minicircle was amplified. It is concluded that the infection by L. infantum occurs in cats in the State of Paraíba, Northeast region of Brazil and the need to understand the immunological profile of the visceral leishmaniasis in the feline population is highlighted with aimed at the control measures in public health.

Resumo Descrevem-se os principais aspectos clínicos, anatomopatológicos e moleculares da infecção por Leishmania infantum em dois gatos, cuja queixa era de lesões cutâneas multicêntricas, nodulares e ulceradas. Os animais foram submetidos à avaliação clínica, seguida de exames sorológicos, molecular e parasitológico, com cultura e isolamento do parasita e posterior caracterização isoenzimática. Os animais foram eutanasiados e encaminhados para a necropsia. O caso 1 era uma gata adulta, sem raça definida e errante. O caso 2 era um gato adulto, sem raça definida e domiciliado. Ambos foram positivos para a presença de anticorpos anti-L. infantum. Na citologia dos nódulos cutâneos e linfonodos, puderam ser visualizadas formas amastigotas de Leishmania spp. livres e no interior de macrófagos. Na histopatologia, as lesões se caracterizavam por dermatite granulomatosa nodular e/ou ulcerativa, associadas a formas amastigotas de Leishmania spp. Por meio da reação em cadeia da polimerase, amplificou-se a sequência do minicírculo do kDNA de L. infantum. Conclui-se que a infecção por L. infantum ocorre em gatos no estado da Paraíba, região Nordeste do Brasil. Deve-se ressaltar a necessidade de compreender o perfil imunológico e epidemiológico da leishmaniose visceral na população felina, com vistas às medidas de controle em saúde pública.

Animals , Male , Female , Cats , Cat Diseases/diagnosis , Leishmania infantum/genetics , Leishmaniasis, Visceral/diagnosis , Leishmaniasis, Visceral/transmission , Leishmaniasis, Visceral/veterinary , Brazil , Antibodies, Protozoan/blood , Polymerase Chain Reaction/veterinary , DNA, Kinetoplast/genetics , Euthanasia, Animal , Macrophages/parasitology
Rev. Soc. Bras. Med. Trop ; 53: e20190169, 2020.
Article in English | LILACS | ID: biblio-1057265


Abstract INTRODUCTION: Leishmania infantum was considered to be absent from Amapá until 2017 when canine infection was detected. However, there is a lack of knowledge about which reservoir species are involved in transmission in this region. METHODS: Between 2014 and 2016, 86 samples from wild mammals and 74 from domestic dogs were collected in Wajãpi Indigenous Territory and were tested for the presence of deoxyribonucleic acid (DNA) of Leishmania. RESULTS: The DNA of Le. infantum was detected in two rodent samples, Dasyprocta sp. and Proechimys cuvieri. CONCLUSIONS: This is the first evidence characterizing a sylvatic transmission cycle of Le. infantum in the State of Amapá.

Animals , Dogs , Rodentia/parasitology , Disease Reservoirs/veterinary , Leishmania infantum/genetics , Dog Diseases/epidemiology , Leishmaniasis, Visceral/epidemiology , Brazil/epidemiology , DNA, Protozoan , Leishmania infantum/isolation & purification , Dog Diseases/parasitology , Leishmaniasis, Visceral/transmission
Rev. Soc. Bras. Med. Trop ; 53: e20190320, 2020. tab, graf
Article in English | LILACS | ID: biblio-1057289


Abstract INTRODUCTION: This study aimed to investigate human exposure to Leishmania spp. infection and sandflies in an area endemic for the disease. METHODS: The presence of antibodies specific for Leishmania spp. and saliva of Lutzomyia spp. and that of L. infantum DNA in blood were evaluated. RESULTS: Antibodies against Leishmania spp. and sandfly saliva were observed in 20.8% and 37.7% of individuals, respectively. DNA of Leishmania spp. was amplified from the blood of one patient. CONCLUSIONS: The results suggest that Leishmania spp. infection may be underdiagnosed in this area.

Humans , Animals , Male , Female , Adolescent , Adult , Aged , Young Adult , Psychodidae/parasitology , Insect Vectors/parasitology , Leishmania/isolation & purification , Leishmaniasis, Visceral/transmission , Brazil , Enzyme-Linked Immunosorbent Assay , Polymerase Chain Reaction , Leishmania/genetics , Leishmania/immunology , Leishmaniasis, Visceral/epidemiology , Middle Aged
Rev. bras. parasitol. vet ; 28(4): 569-573, Oct.-Dec. 2019. tab, graf
Article in English | LILACS | ID: biblio-1058005


Abstract Phlebotomines of the genus Lutzomyia are important vector for species of Leishmania, the etiological agent of leishmaniasis. The aim of this study was to assess the diversity of sandflies in an endemic area for Visceral Leishmaniasis (VL). Sampling was performed in four localities on the coast of the municipality of Goiana, state of Pernambuco, Northeastern Brazil. Specimens were collected monthly on three consecutive nights, from November 2017 to October 2018. CDC light traps were installed at a height of 1.5 m above the ground, in two ecotypes (i.e. tree and animal facility), both in peridomestic areas. A total of 5,205 sandflies were collected, among which the species Lutzomyia longipalpis (99.85%; 5,197/5,205) was the most common, followed by Lutzomyia evandroi (0.13%; 07/5,205) and Lutzomyia whitmani (0.02%; 01/5,205). Specimens of L. longipalpis were collected throughout the study period and most of them were found near to the animal facilities. The findings from this research indicate that vectors for Leishmania infantum are present in the study area throughout the year, along with occurrences of vectors relating to Cutaneous Leishmaniasis (CL). Preventive vector control measures need to be implemented in Goiana to reduce the risk of infection for the human and animal populations.

Resumo Flebotomíneos do gênero Lutzomyia são importantes vetores de espécies de Leishmania, agente etiológico das leishmanioses. O objetivo deste estudo foi avaliar a diversidade de flebotomíneos em área endêmica para Leishmaniose Visceral (LV). As coletas foram realizadas em quatro localidades do litoral do município de Goiana, Pernambuco, Nordeste do Brasil. Os espécimes foram coletados mensalmente em três noites consecutivas de novembro de 2017 a outubro de 2018. Foram instaladas armadilhas luminosas modelo CDC a uma altura de 1,5 m acima do solo em dois ecótopos (ex. árvore e instalações de animais), ambos em áreas peridomiciliares. Um total de 5.205 flebotomíneos foi coletado, sendo Lutzomyia longipalpis (99,85%; 5.197/5.205) a mais comum, seguida por Lutzomyia evandroi (0,13%; 07/5.205) e Lutzomyia whitmani (0,02%; 01/5.205). L. longipalpis foi coletada durante todo o período do estudo. A maioria dos espécimes foi detectada perto das instalações dos animais. Os achados deste estudo indicam a presença de vetores de Leishmania infantum na área avaliada ao longo do ano, bem como a ocorrência de vetores relacionados à Leishmaniose Cutânea (LC). Medidas preventivas de controle vetorial devem ser implementadas em Goiana para reduzir o risco de infecção à população humana e animal.

Animals , Male , Female , Psychodidae/classification , Insect Vectors/classification , Seasons , Brazil , Population Density , Endemic Diseases , Leishmaniasis, Visceral/transmission
Rev. Soc. Bras. Med. Trop ; 52: e20180474, 2019. tab, graf
Article in English | LILACS | ID: biblio-990440


Abstract INTRODUCTION: Leishmaniasis is a complex vector-borne infectious diseases caused by protozoan parasites in the genus Leishmania and spread by hematophagous phlebotomine sand flies (Diptera: Psychodidae, Phlebotominae). The aim of this study was to investigate the phlebotomine fauna, endophily and exophily of the species found, and possible influence of climatic factors on their populations. METHODS: The study was conducted in the Xakriabá Indigenous Reserve (XIR) in the municipality of São João das Missões in northern Minas Gerais state, Brazil. Insects were collected over three consecutive nights in the last week of each month for 12 months from July 2015 to May 2016 from four houses in four different villages. Two traps were set up in each house: one in the intra-domicile and another in the peri-domicile. RESULTS: A total of 2,012 phlebotomine sand fly specimens representing 23 species and belonging to 10 different genera were captured and identified. Among the studied villages, Riacho do Brejo showed the highest density and diversity of phlebotomine sand flies. The species Lutzomyia longipalpis (80.3%) and Nyssomyia intermedia (7.3%), which are major vectors of visceral and cutaneous leishmaniasis, respectively, had the highest population densities, both in the intra- and peri-domicile. No correlation was observed between climatic factors and the density of phlebotomine sand flies. CONCLUSIONS: The results of the present study may contribute to a better understanding and targeting of the measures for preventing and controlling leishmaniasis by the authorities responsible for indigenous health.

Animals , Male , Female , Psychodidae/physiology , Leishmaniasis, Cutaneous/transmission , Conservation of Natural Resources , Insect Vectors/physiology , Leishmaniasis, Visceral/transmission , Seasons , Time Factors , Brazil , Analysis of Variance , Population Density , Sex Distribution , Ecosystem , Animal Distribution
Braz. j. biol ; 78(4): 609-614, Nov. 2018. tab, graf
Article in English | LILACS | ID: biblio-951605


Abstract Zoonotic visceral leishmaniasis (ZVL), caused by protozoans of the genus Leishmania, it is a worldwide of great importance disease. In the northeast region of Brazil, the state of Alagoas has an endemic status for ZVL. Thus, this work aimed to analyze the epidemiological situation of human and canine visceral leishmaniasis in Alagoas, Northeast, Brazil, from 2007 to 2013. We conducted a descriptive, observational, retrospective study using secondary data from the Notifiable Diseases Information System, the Center of Zoonosis Control of Maceió, and the Central Laboratory of Public Health of Alagoas. During the studied period, it was observed that the highest incidence of human visceral leishmaniasis was in 2011 and the lowest in 2013. On the other hand, canine visceral leishmaniasis had its highest incidence in 2007 and its lowest in 2012. Of the 55 municipalities in the State of Alagoas that showed human visceral leishmaniasis (HVL), São José da Tapera presented an average of 4.4 cases over the past five years, being classified as of intense transmission. Regarding canine visceral leishmaniasis, in the same studied period, 45,112 dogs were examined in the State, of which 4,466 were positive. It resulted, thus, in a 9.9% positivity rate. Conclusions: Our data are important because canine infection is an important risk factor for the human disease.

Resumo Leishmaniose visceral zoonótica, causada por protozoários do gênero Leishmania, é uma doença importante no mundo. Na região nordeste do Brasil, do estado de Alagoas é endêmico para LVZ. Neste sentido, este trabalho teve como objetivo analisar a situação epidemiológica da leishmaniose visceral humana e canina em Alagoas, Nordeste, Brasil, no período de 2007 a 2013. Foi realizado um estudo descritivo, observacional, retrospectivo, usando-se secundário do Sistema de Informação de Agravos de Notificação (SINAN), Centro de Controle de Zoonoses de Maceió (CCZ) e Laboratório Central de Saúde Pública de Alagoas (LACEN/AL). Durante o período de estudo, observou-se que o ano de maior incidência de Leishmaniose visceral humana (LVH) foi o de 2011 e o de menor foi no ano de 2013. Já a LVC teve maior incidência em 2007 e menor em 2012. Dos 55 municípios do Estado de Alagoas que apresentaram LVH, São José da Tapera apresentou uma média de casos de 4,4 nos últimos cinco anos classificado como de transmissão intensa; No que diz respeito à leishmaniose visceral canina (LVC), no mesmo período de estudo, foram examinados 45.112 cães no Estado, dos quais 4.466 foram positivos. Resultou assim, em uma taxa de 9,9% de positividade. Nossos dados são importantes porque a infecção canina é um importante fator de risco para a doença humana.

Humans , Animals , Male , Female , Infant , Child , Adult , Middle Aged , Dogs , Endemic Diseases/veterinary , Endemic Diseases/statistics & numerical data , Dog Diseases/epidemiology , Neglected Diseases/epidemiology , Leishmaniasis, Visceral/veterinary , Leishmaniasis, Visceral/epidemiology , Brazil/epidemiology , Disease Reservoirs/parasitology , Risk Factors , Cities , Disease Progression , Dog Diseases/parasitology , Dog Diseases/transmission , Leishmaniasis, Visceral/transmission
ABCS health sci ; 43(1): 10-13, maio 18, 2018. tab, mapas
Article in Portuguese | LILACS | ID: biblio-883995


INTRODUÇÃO: A leishmaniose Visceral (LV) é uma antropozoonose causada pela Leishmania infantum que avança nos últimos trinta anos a passos largos em sentido ao ambiente urbano. Desde 1977 há registros da doença em áreas periféricas do município do Rio de Janeiro, entretanto em 2011 foi descrita no bairro do Caju por meio do diagnóstico do parasita em cães infectados e da captura de espécimes de seu principal vetor. OBJETIVO: Este artigo tem por objetivo divulgar o trabalho primário de captura e identificação entomológica destes espécimes que proporcionou ações de vigilância no primeiro foco ativo urbano de LV na cidade do Rio de Janeiro, citado recentemente em diversos estudos, mas ainda não publicizado em todos os seus detalhes. MÉTODOS: As armadilhas luminosas CDC adaptadas foram instaladas de forma setorizada em área circular de 1000 m de raio a partir do suposto ponto focal, das 17h00m às 07h00m da manhã seguinte, entre junho e setembro de 2011. RESULTADOS: Foram capturados 253 espécimes de Lutzomyia longipalpis, dos quais 63,1% na área do canil, considerado o foco primário de dispersão dos vetores. CONCLUSÃO: Os resultados descritos corroboram com artigos que indicam a urbanização do principal vetor da LV, salientando a importância de estudos mais detalhados sobre o seu ciclo biológico urbano e a necessidade da mudança dos paradigmas da vigilância das leishmanioses no Brasil.

INTRODUCTION: Leishmaniasis, Visceral (LV) is an anthropozoonosis caused by Leishmania infantum that was advanced in the last thirty years in the urban environment. Since 1977 there are records of the disease in peripheral areas of the municipality of Rio de Janeiro, however, in 2011 it was described in the Caju neighborhood by means of the diagnosis of the parasite in infected dogs and the capture of specimens of its main vector. OBJECTIVE: This article aims to disclose the primary work of entomological capture and identification of these specimens that provided surveillance actions in the first urban active focus of LV in the city of Rio de Janeiro, quoted recently in several studies, but not publicized in all its details. METHODS: The adapted CDC light traps were installed in a circular sector of 1000 m radius from the supposed focal point, from 5:00 p.m. to 7:00 p.m. the following morning, between June and September 2011. RESULTS: A total of 253 specimens of Lutzomyia longipalpis were collected, 63.1% of which in the kennel area, considered the primary focus of dispersion of the vectors. CONCLUSION: The results described corroborate articles indicating the urbanization of the main vector of LV, stressing the importance of more detailed studies of its urban life cycle and the need of the changing paradigms of leishmaniasis surveillance in Brazil.

Animals , Dogs , Psychodidae/pathogenicity , Urbanization , Entomology , Environmental Health Surveillance , Leishmaniasis, Visceral/transmission
Rev. saúde pública (Online) ; 52: 92, 2018. graf
Article in English | LILACS | ID: biblio-979028


ABSTRACT OBJECTIVE Estimate the coverage of control measures of visceral leishmaniasis and relate them with the occurrence of human visceral leishmaniasis in endemic urban area. METHODS Cases of human and canine visceral leishmaniasis were considered as study population and evaluated by a serological survey conducted in Araçatuba, state São Paulo, from 2007 to 2015. The cases of human visceral leishmaniasis were geocoded by the address of the patients and the canine disease by the address of the dogs' owners. The coverage of serological survey, euthanasia, and insecticide spraying was calculated, as well as the canine seroprevalence and the incidence rates of human visceral leishmaniasis. The relationship between human visceral leishmaniasis and control measures was evaluated, as well as the seroprevalence by comparing maps and by linear regression. The relationship between the canine and the human disease was also evaluated by the Ripley's K function. RESULTS The incidence rates of human visceral leishmaniasis showed a period of decline (2007 to 2009) and a period of stability (2010 to 2015), a behavior similar to that of canine seroprevalence. In general, the coverage of control measures was low, and the non-association with the incidence of human visceral leishmaniasis can be a result of the period analyzed and of the small number of analyzed units (sectors of the Superintendence for the Control of Endemic Diseases). The distribution of human cases showed spatial dependence with the distribution of seropositive dogs from 2007 to 2009. CONCLUSIONS This study reaffirmed the relationship between the occurrence of the disease in humans and dogs, it verified a decrease in the rates of visceral leishmaniasis in Araçatuba over time, even at low coverage of control activities. However, further studies are needed to determine if factors beyond monitoring and control measures are involved in the reduction of incidences.

RESUMO OBJETIVO Estimar a cobertura das atividades de controle da leishmaniose visceral e relacioná-las com a ocorrência de leishmaniose visceral em humanos em área urbana endêmica. MÉTODOS Foram considerados como população de estudo os casos de leishmaniose visceral em humanos e em cães avaliados por inquérito sorológico censitário realizado em Araçatuba, SP, de 2007 a 2015. Os casos de leishmaniose visceral em humanos foram geocodificados pelo endereço de residência dos pacientes e, os cães, pelo endereço de residências dos respectivos tutores. Foram calculadas as coberturas do inquérito sorológico, da eutanásia e de borrifação de inseticida, as soroprevalências caninas e as taxas de incidência de leishmaniose visceral em humanos. A relação entre a leishmaniose visceral em humanos e as medidas de controle, bem como a soroprevalência foram avaliadas por comparação de mapas e por meio de regressão linear. A relação entre a doença canina e a humana também foi avaliada por meio da função K de Ripley . RESULTADOS As taxas de incidência de leishmaniose visceral em humanos apresentaram um período de declínio (2007 a 2009) e um período de estabilidade (2010 a 2015), comportamento semelhante ao das soroprevalências caninas. Em geral, a cobertura das medidas de controle foi baixa e a não associação com a incidência de leishmaniose visceral em humanos pode ser consequência do período analisado e do número pequeno de unidades analisadas (setores da Superintendência de Controle de Endemias). A distribuição dos casos humanos apresentou dependência espacial com a distribuição dos cães soropositivos de 2007 a 2009. CONCLUSÕES Este trabalho reafirmou a relação entre a ocorrência da doença no homem e no cão, verificou a diminuição das taxas de leishmaniose visceral em humanos e em cães em Araçatuba ao longo do tempo, mesmo em baixa cobertura das atividades de controle. Entretanto, novos estudos são necessários para averiguar se fatores além das atividades de vigilância e controle estariam envolvidos na diminuição das incidências.

Humans , Animals , Infant , Child, Preschool , Child , Adolescent , Adult , Dogs , Young Adult , Dog Diseases/epidemiology , Leishmaniasis, Visceral/veterinary , Leishmaniasis, Visceral/epidemiology , Urban Population , Brazil/epidemiology , Seroepidemiologic Studies , Incidence , Disease Vectors , Dog Diseases/prevention & control , Dog Diseases/blood , Dog Diseases/transmission , Spatio-Temporal Analysis , Leishmaniasis, Visceral/prevention & control , Leishmaniasis, Visceral/transmission , Middle Aged
Mem. Inst. Oswaldo Cruz ; 113(11): e180301, 2018. tab
Article in English | LILACS | ID: biblio-976228


A pivotal strategy to decrease the risk of visceral leishmaniasis in humans is to control the infection and disease progression in dogs, the domestic reservoir of Leishmania infantum (L. chagasi). Immunotherapy is a viable approach to treat sick dogs because cell-mediated immunity is the principal defense mechanism against L. infantum. Domperidone is an immune-stimulatory drug increasingly used in veterinary medicine as a prophylactic or immunotherapeutic agent. Domperidone treatment has shown to prevent overt disease or improve the clinical condition of infected dogs. However, veterinarians should be aware of the potential cardiotoxicity of domperidone when given together with drugs that inhibit CYP450s liver enzymes or those that prolong the QT interval. On the other hand, learning whether domperidone treatment significantly decreases dog infectivity to sand fly vectors is of capital importance since this result should have a palpable impact on the infection risk of humans living in regions endemic for visceral leishmaniasis.

Animals , Dogs , Leishmaniasis, Visceral/diagnosis , Leishmaniasis, Visceral/therapy , Leishmaniasis, Visceral/transmission , Domperidone/therapeutic use
Cad. Saúde Pública (Online) ; 34(1): e00021117, 2018. tab, graf
Article in Portuguese | LILACS | ID: biblio-889866


Resumo: Foi avaliada a associação entre características ambientais obtidas por sensoriamento remoto e a prevalência da leishmaniose visceral canina (LVC) no bairro do Jacaré, área de recente introdução da doença, no Município de Niterói, Estado do Rio de Janeiro, Brasil. Trata-se de um estudo seccional para avaliação da prevalência de LVC, definida por meio da positividade no teste imunocromatográfico rápido em dupla plataforma (dual path platform - DPP), confirmada com o ensaio imunoenzimático (EIE). Foram incluídos 97 cães com prevalência de LVC de 21,6%. Houve maior frequência de LVC em cães com a convivência com outro cão, gambá, mico e ouriço-terrestre, assim como com a história de remoção de outros cães com LVC do domicílio. Na análise multivariada, ajustada por sexo e idade do cão, cães residentes em áreas com maior cobertura de vegetação esparsa apresentaram prevalência da infecção por Leishmania infantum cinco vezes maior do que aqueles que residiam em áreas menos vegetadas (OR = 5,72; IC95%: 1,47-22,20). Por outro lado, áreas mais urbanizadas caracterizadas como comerciais ou residenciais carentes, identificadas pelo sensoriamento remoto como aquelas com alta densidade de estruturas cinza, estiveram associadas à menor ocorrência da LVC (OR = 0,09; IC95%: 0,01-0,92). A maior prevalência de infecção em cães convivendo com outros animais silvestres e em áreas com maior cobertura vegetal, associada com menor prevalência em áreas urbanizadas, indica um padrão rural de transmissão da LVC nessa área.

Resumen: Se evaluó la asociación entre las características ambientales obtenidas por teledetección y la prevalencia de la leishmaniosis visceral canina (LVC) en el barrio de Jacaré, área de reciente introducción de la enfermedad, en el municipio de Niteroi, Estado de Río de Janeiro, Brasil. Se trata de un estudio seccional para la evaluación de la prevalencia de LVC, definida mediante la positividad en el test inmunocromatográfico rápido en una plataforma de doble vía (dual path platform - DPP), confirmada con un ensayo imunoenzimático (EIE). Se incluyeron a 97 perros con una prevalencia de LVC de un 21,6%. Hubo una mayor frecuencia de LVC en perros que conviven con otros perros, zarigüeyas, monos y erizos terrestres, así como con el historial de retirada de otros perros con LVC del domicilio. En el análisis multivariado, ajustado por sexo y edad del perro, los perros residentes en áreas con una mayor cobertura de vegetación muy dispersa presentaron una prevalencia de infección por Leishmania infantum cinco veces mayor que aquellos que residían en áreas con menos vegetación (OR = 5,72; IC95%: 1,47-22,20). Por otro lado, las áreas más urbanizadas, caracterizadas como comerciales o residenciales con pocos recursos, identificadas mediante teledetección como aquellas con una alta densidad de estructuras en gris, estuvieron asociadas a una menor ocurrencia de la LVC (OR = 0,09; IC95%: 0,01-0,92). La mayor prevalencia de infección en perros, conviviendo con otros animales silvestres y en áreas con una mayor superficie vegetal, se asocia con una menor prevalencia en áreas urbanizadas, lo que indica un padrón rural de transmisión de la LVC en ese área.

Abstract: The study assessed the association between environmental characteristics obtained by remote sensing and prevalence of canine visceral leishmaniasis (CVL) in the neighborhood of Jacaré, an area with recent introduction of the disease in the municipality (county) of Niterói, Rio de Janeiro State, Brazil. This was a cross-sectional study to assess CVL prevalence, defined as a positive result in the dual path platform (DPP) rapid immunochromatographic assay, confirmed by immunoenzymatic assay (IEA). The study included 97 dogs, with 21.6% CVL prevalence. CVL prevalence was higher in dogs with contact with another dog, opossum, marmoset, or hedgehog, as well as history of culling of other dogs with CVL from the household. In the multivariate analysis, adjusted for the dog's sex and age, dogs in areas with sparse vegetation showed fivefold higher prevalence of Leishmania infantum infection compared to dogs in areas with less vegetation (OR = 5.72; 95%CI: 1.47-22.20). Meanwhile, less urbanized areas, characterized as commercial or low-income residential areas, identified by remote sensing as those with high density of gray structures, were associated with lower CVL prevalence (OR = 0.09; 95%CI: 0.01-0.92). The higher prevalence of infection in dogs living alongside wild animals and in areas with more vegetation and lower prevalence in more urbanized areas suggest a rural transmission pattern for CVL in this area.

Animals , Male , Female , Dogs , Dog Diseases/epidemiology , Leishmaniasis, Visceral/veterinary , Opossums , Brazil/epidemiology , Residence Characteristics , Prevalence , Risk Factors , Leishmania infantum , Dog Diseases/transmission , Leishmaniasis, Visceral/transmission , Leishmaniasis, Visceral/epidemiology
Rio de Janeiro; s.n; 2018. 61 f p. tab, graf, il.
Thesis in Portuguese | LILACS | ID: biblio-966936


A cada ano ocorrem aproximadamente 50 a 90 mil novos casos de leishmaniose visceral (LV). Mais de 90% dos casos de LV ocorrem em sete países no mundo: Brasil, Etiópia, Índia, Quênia, Somália, Sudão do Sul e Sudão. Na América Latina, 96% ocorrem no Brasil. A coinfecção LV-HIV tem sido considerada como doença emergente em várias regiões do mundo em função da superposição geográfica das duas infecções como consequência da urbanização das leishmanioses e da interiorização da infecção por HIV. A coinfecção LV-HIV geralmente resulta em respostas desfavoráveis ao tratamento, frequentes recidivas e óbitos prematuros. Este estudo teve como objetivo descrever e analisar o perfil clínicoepidemiológico e a distribuição espacial e temporal da coinfecção da LV-HIV em Teresina/PI, de 2006 a 2015. Trata-se de um estudo seccional, com dimensão temporal, desenvolvido a partir de dados espaciais georreferenciados para o endereço do domicílio de residência referentes aos casos de LV e LV-HIV notificados e confirmados no Sistema de Informação de Agravos de Notificação (SINAN). Do total de casos de LV notificados no período do estudo (737), 19,4% eram de coinfecção LV-HIV. A proporção de casos da coinfecção LV-HIV em relação aos casos de LV foi de 8,6%, em 2006 e 47,7% em 2015, o coeficiente de incidência foi de 0,87 casos por 100.000 habitantes e 2,49 casos por 100.00 habitantes, para os mesmos períodos. Destaca-se a diferença entre o diagnóstico clínico e laboratorial entre os dois grupos sendo fraqueza, emagrecimento, quadro infeccioso e fenômenos hemorrágicos as manifestações clínicas mais frequentes nos casos com LV-HIV. A letalidade e a recidiva foram, aproximadamente, duas vezes maiores nesse grupo, 11,4% e 13,3%, respectivamente. Foi evidenciada maior agregação espacial dos casos LV-HIV em relação àquela observada para os casos de LV. Os resultados apresentados neste estudo contribuem para o conhecimento sobre o diagnóstico clínicoepidemiológico e o processo de ocorrência da coinfecção LV-HIV, potencializando ações de prevenção e planejamento em saúde

Each year occur approximately 50 to 90 thousand new cases of visceral leishmaniasis (VL). More than 90% of the cases of VL occur in seven countries of the world: Brazil, Ethiopia, India, Kenya, Somalia, Sudan and South Sudan. In Latin America, 96% occur in Brazil. The VL-HIV coinfection has been considered as emerging disease in several regions of the world depending on the geographical overlap of both infections as a result of leishmaniasis urbanization and HIV infection interiorization. The VL-HIV coinfection usually results in unfavorable treatment responses, frequent relapses and premature deaths. The objective of this study was to describe and analyze the clinical and epidemiologic profiles and the spatial and temporal distribution of VL-HIV coinfection in Teresina/PI, from 2006 to 2015. It is a cross-sectional study, with temporal dimension, developed from geo-referenced data for the address of residence domicile concerning notified and confirmed VL and VL-HIV cases in the Brazilian Disease Information System. From the total number of cases of LV notified within the period of the study (737), 19.4% were of VL-HIV coinfection. The proportion of VL-HIV cases coinfection in relation to LV cases was 8.6% in 2006 and 47.7% in 2015, the coefficient of incidence was 0.87 cases per 100,000 inhabitants and 2.49 cases per 100.00 inhabitants, in the same periods. Highlights the clinical and laboratory diagnosis difference between the two groups with weakness, weight loss, infection and hemorrhagic phenomena the most frequent clinical manifestations in patients with LV-HIV. The mortality and recurrence were approximately two times higher in this group, 11.4% and 13.3%, respectively. It was evidenced greater VL-HIV spatial aggregation cases in relation to that observed for LV cases. The results presented in this research contributes to the knowledge about the clinical and epidemiological diagnosis and the process of VL-HIV coinfection occurrence, potentiating prevention and health planning actions

Humans , Brazil , Epidemiologic Studies , Public Health , HIV , Geographic Information Systems/statistics & numerical data , Coinfection/epidemiology , Health Information Systems/statistics & numerical data , Leishmaniasis, Visceral/transmission
Mem. Inst. Oswaldo Cruz ; 112(10): 674-680, Oct. 2017. tab, graf
Article in English | LILACS | ID: biblio-894836


BACKGROUND Visceral leishmaniasis (VL) is an endemic disease in northeastern Argentina including the Corrientes province, where the presence of the vector and canine cases of VL were recently confirmed in December 2008. OBJECTIVES The objective of this study was to assess the modelling of micro- and macro-habitat variables to evaluate the urban environmental suitability for the spatial distribution of Lutzomyia longipalpis presence and abundance in an urban scenario. METHODS Sampling of 45 sites distributed throughout Corrientes city (Argentina) was carried out using REDILA-BL minilight traps in December 2013. The sampled specimens were identified according to methods described by Galati (2003). The analysis of variables derived from the processing of satellite images (macro-habitat variables) and from the entomological sampling and surveys (micro-habitat variables) was performed using the statistical software R. Three generalised linear models were constructed composed of micro- and macro-habitat variables to explain the spatial distribution of the abundance of Lu. longipalpis and one composed of micro-habitat variables to explain the occurrence of the vector. FINDINGS A total of 609 phlebotominae belonging to five species were collected, of which 56% were Lu. longipalpis. In addition, the presence of Nyssomyia neivai and Migonemya migonei, which are vectors of tegumentary leishmaniasis, were also documented and represented 34.81% and 6.74% of the collections, respectively. The explanatory variable normalised difference vegetation index (NDVI) described the abundance distribution, whereas the presence of farmyard animals was important for explaining both the abundance and the occurrence of the vector. MAIN CONCLUSIONS The results contribute to the identification of variables that can be used to establish priority areas for entomological surveillance and provide an efficient transfer tool for the control and prevention of vector-borne diseases.

Animals , Psychodidae/classification , Population Density , Ecosystem , Insect Vectors/classification , Leishmaniasis, Visceral/transmission , Argentina , Urban Population , Spatial Analysis
Rev. Soc. Bras. Med. Trop ; 50(4): 483-488, July-Aug. 2017. tab
Article in English | LILACS | ID: biblio-896987


Abstract INTRODUCTION The control of reservoirs for Leishmania infantum -induced zoonotic visceral leishmaniasis requires the identification of dogs posing a population risk. Here, we assessed the performance of several assays to identify Lutzomyia longipalpis infectious dogs. METHODS We evaluated 99 dogs that were positive for visceral leishmaniasis based on parasite identification. Serological analyses were performed using an enzyme-linked immunosorbent assay, immunofluorescence antibody tests in 1:40 and 1:80 dilutions, rapid dual path platform tests, immunochromatographic assay with a recombinant rK39 antigen, fast agglutination screening tests, and direct agglutination tests. We also performed PCR to analyze peripheral blood and xenodiagnosis. RESULTS Forty-six dogs infected at least one L. longipalpis specimen. Although the serological test sensitivities were above 85% for detecting L. longipalpis infectious dogs, none showed a satisfactory performance, as both specificity (0.06 to 13%) and the area under the receiver operating characteristic curve (45 to 53%) were low. The PCR results were also weak, with a sensitivity of 30%, specificity of 72%, and an area under the receiver operating characteristic curve of 51%. The infected L. longipalpis proportion was higher among asymptomatic dogs than symptomatic dogs. Among the symptomatic dogs, those with ulceration-free skin diseases were more infectious, with an odds ratio of 9.3 (confidence interval of 1.10 - 428.5). The larger the number of insects fed, the greater the detected infectiousness. CONCLUSIONS Our study supports the imperative to develop novel technologies for identifying the infectious dogs that transmit L. infantum for the benefit of public health.

Humans , Animals , Male , Dogs , Psychodidae/parasitology , Serologic Tests/veterinary , Antibodies, Protozoan/blood , Leishmania infantum , Dog Diseases/diagnosis , Mosquito Vectors/parasitology , Leishmaniasis, Visceral/veterinary , Serologic Tests/methods , Sensitivity and Specificity , Dog Diseases/parasitology , Dog Diseases/transmission , Leishmaniasis, Visceral/diagnosis , Leishmaniasis, Visceral/parasitology , Leishmaniasis, Visceral/transmission
Mem. Inst. Oswaldo Cruz ; 112(3): 161-174, Mar. 2017. tab, graf
Article in English | LILACS | ID: biblio-841774


Lutzomyia longipalpis s.l. is a complex of sibling species and is the principal vector of American visceral leishmaniasis. The present review summarises the diversity of efforts that have been undertaken to elucidate the number of unnamed species in this species complex and the phylogenetic relationships among them. A wide variety of evidence, including chemical, behavioral and molecular traits, suggests very recent speciation events and complex population structure in this group. Although significant advances have been achieved to date, differential vector capacity and the correlation between structure of parasite and vector populations have yet to be elucidated. Furthermore, increased knowledge about recent epidemiological changes, such as urbanisation, is essential for pursuing effective strategies for sandfly control in the New World.

Animals , Psychodidae/classification , Psychodidae/genetics , Species Specificity , Genes, Insect , Biodiversity , Insect Vectors/classification , Insect Vectors/genetics , Leishmaniasis, Visceral/transmission , Phylogeny , Polymorphism, Genetic , Polymorphism, Restriction Fragment Length , Brazil
Rev. saúde pública ; 51: 49, 2017. tab, graf
Article in English | LILACS | ID: biblio-845899


ABSTRACT OBJECTIVE To analyze the determinants for the occurrence of human visceral leishmaniasis linked to the conditions of vulnerability. METHODS This is an ecological study, whose spatial analysis unit was the Territorial Analysis Unit in Araguaína, State of Tocantins, Brazil, from 2007 to 2012. We have carried out an analysis of the sociodemographic and urban infrastructure situation of the municipality. Normalized primary indicators were calculated and used to construct the indicators of vulnerability of the social structure, household structure, and urban infrastructure. From them, we have composed a vulnerability index. Kernel density estimation was used to evaluate the density of cases of human visceral leishmaniasis, based on the coordinates of the cases. Bivariate global Moran’s I was used to verify the existence of spatial autocorrelation between the incidence of human visceral leishmaniasis and the indicators and index of vulnerability. Bivariate local Moran’s I was used to identify spatial clusters. RESULTS We have observed a pattern of centrifugal spread of human visceral leishmaniasis in the municipality, where outbreaks of the disease have progressively reached central and peri-urban areas. There has been no correlation between higher incidences of human visceral leishmaniasis and worse living conditions. Statistically significant clusters have been observed between the incidences of human visceral leishmaniasis in both periods analyzed (2007 to 2009 and 2010 to 2012) and the indicators and index of vulnerability. CONCLUSIONS The environment in circumscribed areas helps as protection factor or increases the local vulnerability to the occurrence of human visceral leishmaniasis. The use of methodology that analyzes the conditions of life of the population and the spatial distribution of human visceral leishmaniasis is essential to identify the most vulnerable areas to the spread/maintenance of the disease.

RESUMO OBJETIVO Analisar determinantes para a ocorrência da leishmaniose visceral humana vinculados às condições de vulnerabilidade. MÉTODOS Estudo ecológico, cuja unidade de análise espacial foi a Unidade de Análise Territorial em Araguaína, TO, de 2007 a 2012. Foi realizada análise da situação sociodemográfica e de infraestrutura urbana no município. Indicadores primários normalizados foram calculados e utilizados na construção de indicadores de vulnerabilidade de estrutura social, de estrutura domiciliar e de infraestrutura urbana. A partir deles, foi composto um índice de vulnerabilidade. A estimativa de Kernel foi utilizada para avaliar a densidade de casos de leishmaniose visceral humana, com base nas coordenadas dos casos. O I-Moran Global Bivariado foi empregado para verificar a existência de autocorrelação espacial entre a incidência de leishmaniose visceral humana e os indicadores e índice de vulnerabilidade. I-Moran Local Bivariado foi utilizado para identificar clusters espaciais. RESULTADOS Foi observado um padrão de disseminação centrífuga da leishmaniose visceral humana no município, em que surtos da doença atingiram progressivamente áreas centrais e periurbanas. Houve correlação entre maiores incidências de leishmaniose visceral humana e piores condições de vida. Foram observados clusters estatisticamente significativos entre as incidências de leishmaniose visceral humana nos dois períodos analisados (2007 a 2009 e 2010 a 2012) e os indicadores e índice de vulnerabilidade. CONCLUSÕES O ambiente em áreas circunscritas contribui como fator de proteção ou aumenta a vulnerabilidade local à ocorrência de leishmaniose visceral humana. O uso de metodologia que analisa as condições de vida da população e distribuição espacial da leishmaniose visceral humana é essencial na identificação de áreas mais vulneráveis à disseminação/manutenção da doença.

Humans , Male , Female , Leishmaniasis, Visceral/transmission , Urban Population/statistics & numerical data , Vulnerable Populations/statistics & numerical data , Brazil/epidemiology , Cluster Analysis , Family Characteristics , Incidence , Leishmaniasis, Visceral/epidemiology , Risk Factors , Socioeconomic Factors , Spatio-Temporal Analysis , Time Factors
Rev. Soc. Bras. Med. Trop ; 49(6): 772-773, Dec. 2016.
Article in English | LILACS | ID: biblio-1041388


Abstract: INTRODUCTION: The present note discusses some evidence on the increasing potential risk for American visceral leishmaniasis (AVL) transmission in the Northern Brazilian State of Amapá, the Guianan-Amazon biome. METHODS Early and present data about AVL were collected, including our recent entomological findings. RESULTS: The spread of the sand fly vector Lutzomyia longipalpis, and a sylvatic reservoir host, the crab-eating fox Cerdocyon thous in that region represents important findings related to the epidemiology of AVL in the Guianan-Amazon biome. CONCLUSIONS: These observations suggest that Brazilian authorities need to develop surveillance strategies in these risk areas.

Humans , Animals , Male , Psychodidae/parasitology , Leishmania donovani/isolation & purification , Disease Reservoirs , Foxes/parasitology , Insect Vectors/parasitology , Leishmaniasis, Visceral/transmission , Brazil/epidemiology , Leishmaniasis, Visceral/epidemiology
Rev. Soc. Bras. Med. Trop ; 49(6): 698-702, Dec. 2016. tab, graf
Article in English | LILACS | ID: biblio-829670


Abstract INTRODUCTION: The sandfly fauna is well studied globally. In Brazil, sandfly fauna is very diverse in the Northeast region, especially in states such as Maranhão, Ceará, and Bahia. However, in the State of Pernambuco, the distribution of these insects is still not well known. Therefore, the objective of this study was to identify the different species that constitute the sandfly fauna in an urban area in the Northeast region of Brazil, where an outbreak of visceral leishmaniasis (VL) was recently reported. METHODS: The sandflies were collected from an urban area endemic for VL, at five collection points. The collection of samples was carried out from November 2014 to December 2015, using CDC light traps installed in intradomiciliary and peridomiciliary fashion. RESULTS: The collected sandflies (n = 297) belonged to eight species: Lutzomyia lenti, Lutzomyia longipalpis, Lutzomyia sallesi, Lutzomyia migonei, Lutzomyia walkeri, Lutzomyia capixaba, Lutzomyia carmelinoi, and Lutzomyia whitmani. Most of the specimens collected were peridomiciliary (247/297, 83%). L. lenti (154/297, 52%) was the most frequently sampled species, followed by L. longipalpis (88/297, 29.6%), and L. sallesi (42/297, 14.1%), which together accounted for over 90% of the collected sandfly specimens. CONCLUSIONS: The continued presence of L. longipalpis in urban areas, including that in intradomiciliary areas, with a predominance of females, is crucial because of the high possibility of them causing VL outbreaks, since this species is the main vector of Leishmania infantum in Brazil.

Animals , Male , Female , Psychodidae/classification , Insect Vectors/classification , Psychodidae/virology , Seasons , Urban Population , Brazil , Population Density , Insect Vectors/virology , Leishmaniasis, Visceral/transmission